渤南低渗油田注水井欠注层伤害机理研究

渤南油田五区沙三段九砂组油藏属中等水敏性和速敏性的地层；油藏为轻质油-稀油油藏。原油具有低密度、低粘度和高凝固点等特点，组分含硫量低；地层水总矿化度较高，水型为NaHCO3型。研究了渤南油田注水井伤害机理，从地层特性、注入水水质、悬浮物堵塞、游离油和乳化油滴、结垢、细菌及以往增产措施等方面评价了可能对储层造成的损坏及损坏程度。渤南油田地层的水敏性、速敏性和低渗透性是注水井损害的内在因素，注水井中悬浮固相颗粒、含油量和细菌严重超标，水质不合格是注水井损害的外在因素；注入水中悬浮固相颗粒和油的含量高，易形成盐酸不溶垢和有机垢；细菌和油质的共同作用增加管路的腐蚀，形成铁垢，逐渐降低地层的渗透率，严重时堵塞地层。

Study of Damage Mechanism of Underinjected Formations in Water-Injecting Wells of Low-Permeability Reservoirs in Bonan Oilfield

The ninth member of the S_3 section in Block Five of Bonan oilfield is characterized by the moderate water sensitivity and velocity sensitivity. The crude oil is characterized by low density, low viscosity and high freezing point. Its component is low sulfur-containing. The total salinity of the formation water is comparably high, averagely 11,100-19,900mg/L, and the type is NaHCO_3. This paper presents a study on the mechanism of the water-injecting wells and assesses the possibility and the damage degree in many aspects, in which includes the formation characteristics of BoNan oilfield, the injected water quality, the suspended substance plugging, the free oil, and the emulsified oil drop, the scaling and bacteria etc. The internal factors of the water-injecting well damage are the water sensetivity and velocity sensitivity and the low permeability.The water quality disqualification is the external factors. The injection water is inclined to scale. The corrosion of the injection water provokes the generation of the iron scale, reducing the formation permeability and even blocking the formation if serious.